Methylene chloride is a known solvent for surface treatment of substrates. It is known for use in degreasing substrates as well as in cleaning substrates in preparation for electroplating conventional metal and plastic substrates. The techniques used to clean such substrates are conventional. Typically, the choice of the appropriate cleaning or preparative cycle depends primarily upon the nature of the substrate to be prepared and the nature and amounts of the soil to be removed. Organic compounds, such as methylene chloride, are used to dissolve most oils and greases including those used to bind buffing and polishing compounds. One typical problem in using organic cleaners is that removal of oils and greases from a highly contaminated surface, may merely leave the non-oily dirt dry and more firmly attached. According to known methods, hot solvent vapors melt or plasticize and reflow the surface of the substrate. This effects clarity in surface finish.
Although organic solvents may be used merely as dips, it is more common and effective to employ vapor degreasing, in which vapors of the solvent condense on the parts to be cleaned and run back into a pool of liquid solvent below them. Methylene chloride is a common solvent for this purpose.
In choosing a vapor degreasing solvent, EPA regulations and relative toxicity must be balanced against cost. In any case, necessary precautions dictate that no one must enter a vapor degreaser for repair or cleaning without life-support and a partner outside for emergencies. Thus, the disadvantage of such a process involves the requirement of specialized equipment to prevent escape of toxic vapors into the work area.
Applicants have developed an adhesion promoting composition, which overcomes disadvantages found in the prior art.